1. Field of the Invention
The present invention is generally in the field of electric motors that receive electrical energy from an energy storage device and that drive a propulsion system.
2. Description of the Related Art
Battery-powered electric motors are well known and have been used to provide rotational energy to drive propulsion systems for vehicles, including, for example, watercraft. In general, vehicles driven by battery-powered electric motors have a limited range or limited performance (e.g., limited velocity and acceleration). In order to provide enhanced performance, additional energy must be supplied to the electric motors in the watercraft or other vehicle. Increasing the power necessitates increasing the voltage or the current or both the voltage and the current provided to the electric motors. However, increasing the current provided to an electric motor increases the resistive power losses in the circuits providing energy to the motor. Increasing the voltage to an electric motor decreases the resistive power losses in the supply circuits; however, high voltages are not desirable in vehicles and are particularly undesirable in a watercraft because of the unavoidable presence of water in proximity to the high voltages.